In a device in which accurate data is requested, such as a server for performing data processing or a telecom-related device, a semiconductor storage apparatus with high reliability is requested.
For the purpose of improving reliability of flash EEPROM (Electrically Erasable Programmable Read-Only Memory), there is conventionally used a method for dividing columns of a memory cell array into a plurality of segment columns and conducting only the selected segment column to a bit line.
Japanese Laid-open Patent Publication No. 05-63164
At the time of writing or reading data, voltage is applied to memory cells in a non-selected state except a selected memory cell. At this time, there is a problem that storage charges of the memory cells in a non-selected state gradually fluctuate and when the memory cell is read out, correct data fails to be read out.